1. Field of The Invention
This invention relates to apparatus for advancing a thin, resilient, generally planar photographic film unit from a film cassette.
2. Description of The Prior Art
The present invention relates to film advancing apparatus of the type adapted to advance a thin sheet of resilient, generally planar, photographic film from a film cassette, preferably subsequent to its exposure.
Film advancing apparatus for moving a generally planar, film unit from a film cassette subsequent to its photographic exposure are generally well known in the art. One example of such an apparatus is shown in U.S. Pat. No. 4,152,063 wherein a pair of laterally spaced members are moved through an exposureopening in a film cassette into frictional engagement with a major surface of an exposed film unit so as to advance it to the exterior of the cassette and into the bite of a pair of processing rollers. Another example is shown in U.S. Pat. No. 3,741,095 wherein the film advancing apparatus includes a pair of laterally spaced members which are mounted for rotation into engagement with a trailing edge of an exposed film unit prior to moving it out of a cassette and into the bite of a pair of processing rollers. Still further, reference may be had to U.S. Pat. No. 3,405,618 wherein is shown a camera having a film advancing apparatus comprised of a friction roll for moving an exposed sheet of photographic film in the form of an image-recording sheet into superposed position with an image-receiving sheet.
One of the problems with the film advancing apparatus described above with reference to the '095 patent is that it is not readily adapted for use with thin film units, i.e., film units having a thickness of 2-4 mils at their trailing edge, because of the relatively large size of its film engaging portion. In other words, if such an apparatus were used with thin film units, there would be a good possibility that more than one film unit would be moved during each operating cycle of the apparatus.
The film advancing apparatus described in the '063 and '618 patents present a problem of providing the film unit engaging member(s) with enough force or torque to move the exposed film unit without also causing that film unit to drag the next adjacent film unit along therewith because of the frictional forces between the two film units. Should this happen, more than one film unit may be moved toward the exterior of the film cassette at a time, or the next adjacent film unit, if physically maintained in place, may be deformed by the frictional forces acting on its entire length during the movement of the exposed film unit.